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ipv6: drop non loopback packets claiming to originate from ::1

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We lack a saddr check for ::1. This causes security issues e.g. with acls
permitting connections from ::1 because of assumption that these originate
from local machine.

Assuming a source address of ::1 is local seems reasonable.
RFC4291 doesn't allow such a source address either, so drop such packets.

Reported-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Acked-by: Eric Dumazet <edumazet@google.com>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Florian Westphal 2017-04-14 20:22:43 +02:00 committed by David S. Miller
parent 71947f0f91
commit 0aa8c13eb5
1 changed files with 5 additions and 2 deletions
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7
net/ipv6/ip6_input.c
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@ -122,11 +122,14 @@ int ipv6_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt
max_t(unsigned short, 1, skb_shinfo(skb)->gso_segs));
/*
* RFC4291 2.5.3
* The loopback address must not be used as the source address in IPv6
* packets that are sent outside of a single node. [..]
* A packet received on an interface with a destination address
* of loopback must be dropped.
*/
if (!(dev->flags & IFF_LOOPBACK) &&
ipv6_addr_loopback(&hdr->daddr))
if ((ipv6_addr_loopback(&hdr->saddr) ||
ipv6_addr_loopback(&hdr->daddr)) &&
!(dev->flags & IFF_LOOPBACK))
goto err;
/* RFC4291 Errata ID: 3480